Carbon nanotube complex molded body and the method of making the same

ABSTRACT

A complex molded body of carbon nanotubes includes a matrix and carbon nanotubes arranged in a given direction in the matrix. The matrix is at least one organic polymer selected from the group consisting of thermoplastic resin, thermosetting resin, rubber, and thermoplastic elastomer. The complex molded body is produced by a method comprising the step of: providing a composition that includes a matrix and carbon nanotubes; applying a magnetic field to the composition to arrange the carbon nanotubes in a given direction; and hardening the composition to produce a complex molded body. The complex molded body has excellent anisotropy in terms of electrical property, thermal property, and mechanical property.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a complex molded body wherecarbon nanotubes are arranged in a given direction in a matrix and amethod of making the complex molded body. The molded body functionsanisotropically in terms of electrical property, thermal property,mechanical property and may be used as electronic parts, thermallyconductive material, and high-strength material.

[0002] Japanese Laid-Open Patent Publication No.5-125619 and JapaneseLaid-Open Patent Publication No.7-216660 disclose a carbon nanotube anda method of making it. According the publications, development of manyinteresting applications, which use specific functions of carbonnanotube, such as an electron-emitting element, a hydrogen storage, athin-film cell, a probe, a micromachine, semiconductor ultra large-scaleintegrated circuit, electrically conductive material, thermallyconductive material, high-strength and high-elasticity material areactively examined.

[0003] A conventional complex molded body of carbon nanotube is obtainedby blending carbon nanotubes in a matrix such as resin, rubber, metal,or ceramic and hardening the composition. In such a complex molded body,carbon nanotubes are basically dispersed at random in the matrix.Accordingly, resultant properties such as mechanical property,electrical property, electron-emitting property are randomly or equallyprovided. In other words, the conventional complex molded body is anisotropic material.

[0004] Carbon nanotubes in the matrix can be oriented in a flowingdirection by molding the composition in a flowing field or shearingfields or by extending the composition. However, in these methods,carbon nanotubes can not be arranged in a thickness direction of theplate-like molded body. The direction of nanotubes can not be controlledin a desired direction.

[0005] Japanese Laid-Open Patent Publication No.11-194134 and JapaneseLaid-Open Patent Publication No.10-265208 propose a carbon nanotubedevice and a method of carbon nanotube film respectively where carbonnanotubes are grown in a given direction in vapor on the catalyticmolecules (such as iron, cobalt, nickel) arranged on the substrate.However, when the carbon nanotubes are arranged on the planar substrateby using these methods, only a device in which carbon nanotubes arearranged perpendicular to the substrate can be obtained. Therefore, tofabricate a device that has a desired form is difficult.

[0006] The object of the present invention is to provide a complexmolded body of carbon nanotubes that has excellent anisotropic functionsin terms of electrical property, thermal property, and mechanicalproperty, and a method of making the complex molded body.

BRIEF SUMMARY OF THE INVENTION

[0007] The complex molded body of carbon nanotubes includes a matrix andcarbon nanotubes that are arranged in the matrix in a given direction.

[0008] Other aspects and advantages of the invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] The invention, together with objects and advantages thereof, maybest be understood by reference to the following description of thepresently preferred embodiments together with the accompanying drawingsin which:

[0010]FIG. 1 is a schematic view of a complex molded body of carbonnanotubes of Example 1;

[0011]FIG. 2 is a cross-sectional view of forming molds in an openedposition;

[0012]FIG. 3 is a cross-sectional view of forming molds where thecomposition is injected in a recess of a mold and two molds are closedtogether;

[0013]FIG. 4 is a cross-sectional view showing that, following FIG. 3, apair of magnets are placed on both sides of the forming mold and amagnetic field is applied to the composition in the recess;

[0014]FIG. 5 is a schematic view of a complex molded body of carbonnanotubes of Example 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Embodiments of the present invention are described in detailbelow.

[0016] A complex molded body of carbon nanotubes is formed such that thecarbon nanotubes are arranged in a matrix in a given direction. Thecomplex molded body may be formed into a desired shape such as a plate,a tube, and a block to be used.

[0017] A type and a manufacturing method of the carbon nanotube for usein the present invention are not particularly limited so long as thecarbon nanotube is made of carbon, it takes a tubular shape, and it hasa diameter on the order of nanometer. For example, the carbon nanotubesmanufactured by the methods disclosed in Japanese Laid-Open PatentPublication No.6-157016, Japanese Laid-Open Patent PublicationNo.6-280116, Japanese Laid-Open Patent Publication No.10-203810, andJapanese Laid-Open Patent Publication No.11-11917 may be used. An arcdischarge process has become generally used for synthesis of carbonnanotubes. However, the use of a laser vaporization process, a thermalcracking process, and a plasma discharge process have recently beenstudied and carbon nanotubes produced by such processes.

[0018] A carbon nanotube has a structure of hexagonal networks of carbonatoms extending in tubular form. The nanotube that has one tubular layeris called single-wall nanotube (called SWNT hereinafter) while thenanotube that has a multiple of tubular layers is called multi-wallnanotube (called MWNT hereinafter). Structure of carbon nanotube isdetermined by a kind of synthesis process or various conditions duringthe process.

[0019] By-products, such as amorphous carbon nanoparticles, fullerenes,and metal nanoparticles, are produced together with carbon nanotubes,and such by-products may remain in the product. However, sincefullerenes are soluble in organic solvents, such as toluene, carbondisulfide, benzene, and chlorobenzene, they can be extracted. Also,carbon nanoparticles and graphite pieces can be removed by formingselective inter-layer compounds of carbon nanoparticles and graphitepieces and sintering them at low temperature, based on the fact thatinterlayer distances between layers of carbon nanotubes are shorter thanthose of carbon nanoparticles and graphite pieces. The decrease intemperature inhibits decrement of carbon nanotubes due to combustion andthus improves a yield of the nanotubes.

[0020] Further, the carbon nanotubes are materials of high aspect ratio.Thus the product often has a complex intertwined structure, depending onthe manufacturing process. In such cases, the carbon nanotubes may bedispersed by ultrasonic dispersion. Preferably, carbon nanotubes arepulverized under a predetermined condition and processed to yieldshorter carbon nanotubes. The pulverization process may include, but isnot limited to, dry pulverization processes such as shearing andgrinding, and ball milling and a homogenizer that use asurfactant-containing water or an organic solvent.

[0021] The carbon nanotube for use in the present invention is notlimited to SWNT or MWNT. Carbon nanotubes such as those containing metalor other inorganic or organic materials; those filled with carbon orother materials; coiled, spired, or fibrillary carbon nanotubes; orso-called nanofibers may also be used. Neither the diameters nor thelengths of the carbon nanotubes are limited. However, with regard tomanufacturing facility and realization of anisotropic function, thecarbon nanotubes preferably have a diameter from 1 to 20 nm and a lengthfrom 50 nm to 100 μm.

[0022] The matrix is a base material in which carbon nanotubes areblended. Examples of the matrix may include resin, rubber, thermoplasticelastomer, adhesive, paint, ink, metal, alloy, ceramic, cement, gel,paper, fiber, web, and nonwoven fabric. The matrix may be selectedaccording to intended required characteristics of the complex moldedbody, such as hardness, mechanical strength, heat resistance, electricalproperties, durability, and reliability. In particular, the matrix ispreferably at least one organic polymer selected from the groupconsisting of thermoplastic resin, thermosetting resin, rubber, andthermoplastic elastomer, due to their molding capability.

[0023] Thermoplastic resin includes polyethylene, polypropylene,ethylene-α-olefin copolymer such as ethylene-propylene copolymer,polymethylpentene, polyvinyl chloride, polyvinylidene chloride,polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol,polyvinyl acetal, fluoropolymers such as polyvinylidene fluoride andpolytetrafluoroethylene, polyethylene terephthalate, polybutyleneterephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile,styrene-acrylonitrile copolymer, ABS resin, polyphenylene ether (PPE)resin and modified PPE resin, aliphatic and aromatic polyamide,polyimide, polyamide imide, polymethacrylic acid and polymethacrylatessuch as polymethyl methacrylate, polyacrylic acids, polycarbonate,polyphenylene sulfide, polysulfone, polyether sulfone, polyethernitrile, polyether ketone, polyketone, liquid crystal polymer, siliconeresin, and ionomer.

[0024] The thermosetting resin includes epoxy resin, phenol resin,acrylic resin, urethane resin, polyimide resin, unsaturated polyesterresin, diallyl phthalate resin, dicycropentadiene resin, andbenzocyclobutene diene. The methods of hardening the thermosetting resinare not limited to thermosetting but include ordinary hardening methods,such as light setting and moisture setting.

[0025] The rubber may be natural rubber or synthetic rubber. Syntheticrubbers may include butadiene rubber, isoprene rubber, styrene-butadienecopolymer rubber, nitrile rubber, hydrogenated nitrile rubber,chloroprene rubber, ethylene-propylene rubber, chlorinated polyethylene,chlorosulfonated polyethylene, butyl rubber and butyl rubber halide,fluorine rubber, urethane rubber, and silicone rubber.

[0026] The thermoplastic elastomer includes styrene-butadiene orstyrene-isoprene block copolymers and hydrogenated polymer thereof,styrene thermoplastic elastomer, olefin thermoplastic elastomer, vinylchloride thermoplastic elastomer, polyester thermoplastic elastomer,polyurethane thermoplastic elastomer, and polyamide thermoplasticelastomer. Thermoplastic resin and thermoplastic elastomer areparticularly preferred since they are recyclable.

[0027] The matrix preferably contains at least one material selectedfrom the group consisting of silicone rubber, epoxy resin, polyimideresin, bis-maleimide resin, benzocyclobutene resin, fluororesin, andpolyphenylene ether resin. More preferably, the matrix contains at leastone material selected from the group consisting of silicone rubber,epoxy resin, and polyimide resin in terms of reliability.

[0028] A polymer alloy of the above-mentioned organic polymers, as wellas additives including a known plasticizer, a filler, a hardener,organic fiber such as carbon fiber, glass fiber, and aramid fiber, astabilizer, a colorant may also be mixed in the matrix.

[0029] To facilitate mixing of carbon nanotubes with the matrix orarrangement of carbon nanotubes in the matrix, an organic solvent suchas methylene chloride or water may be added to decrease the viscosity ofthe composition. Further, a dispersion and stabilization agent such as asurfactant may be used to improve dispersion.

[0030] The amount of carbon nanotubes mixed in the matrix is preferably0.01 to 100 parts by weight relative to 100 parts by weight matrix. Whenthe amount is less than 0.01 parts by weight, the composition hasinadequate anisotropic function. When the amount is more than 100 partsby weight, dispersion of carbon nanotubes in the matrix is worsen. Theamount of carbon nanotubes mixed in the matrix in which the nanotubescan be arranged by a magnetic field and the composition exhibit achievesthe effective anisotropic function is conveniently 0.1 to 20 parts byweight, although the amount may vary depending on a kind of matrixmaterial, other additives, or strength of magnetic field used.

[0031] Further, to improve wettability or adhesion of the carbonnanotubes to the matrix, the surface of the carbon nanotubes ispreferably pretreated with degreasing, washing, or activation processsuch as UV-radiation, corona discharge, plasma treatment, flamingtreatment, and ion implation. In addition, after these surfacetreatments, the surface can be treated with a coupling agent such as asilane-containing agent, a titanium-containing agent, and analminum-containing agent. This facilitates the filling of more carbonnanotubes, so that the resultant complex molded body functions moreeffectively.

[0032] A dispersing method of carbon nanotubes in the matrix is notparticularly limited. For example, when the matrix is a liquid polymer,carbon nanotubes may be mixed in the matrix at a certain amount with ausual mixer or a usual blender. Ultrasonic or vibration may further beapplied to improve dispersion of carbon nanotubes. Preferably, degasprocess is conducted to remove entrained air under vacuum or withpressure.

[0033] When the matrix is a solid polymer in the form of pellet orpowders, carbon nanotubes may be mixed in the matrix at a certain amountwith a usual mixing machine, such as an extruder, a kneader, or aroller.

[0034] The strength of the magnetic field applied to the carbonnanotubes sufficient to arrange them in a given direction is a magneticflux density from 0.05 to 30 tesla. When the magnetic flux density isless than 0.05 tesla, carbon nanotubes can not be arranged in a givendirection sufficiently. When the density is more than 30 tesla, themagnetic field is too strong to improve the arrangement further.Although the magnetic flux density is experimentally determined fromtypes or amount of the matrix and the carbon nanotubes, an intendedshape of complex molded body, and required characteristics of endproducts, the practical range of magnetic flux density for arrangingcarbon nanotubes effectively is from 5 to 20 tesla.

[0035] A device for producing an external magnetic field is, forexample, a permanent magnet, an electromagnet, and a coil. In thepresent invention, carbon nanotubes have diamagnetism and they can bearranged in the direction parallel to magnetic lines of force.Therefore, to apply the magnetic field properly, a north pole and asouth pole of magnets may be placed corresponding to a desiredarrangement direction of tubes. Alternatively, a north pole and a northpole of magnets may be placed so as to face to each other. Or a magnetmay be placed only one side of the composition. Further, magnets may beplaced such that magnetic lines of force are curved. That is, a magneticfield may be applied in any way so long as the magnetic lines of forceare adjusted to achieve the aimed anisotropic function.

[0036] The composition may then be molded into a desired shape, such asa plate, a tube, or a block by press molding, extrusion molding,transfer molding, calendering molding, to form a complex molded body.The composition may be further processed into a thin film by processessuch as painting and printing. Thus, the resultant carbon nanotubecomplex molded body includes carbon nanotubes that are arranged in agiven direction. This can be confirmed in an enlarged picture with anelectron microscope.

[0037] The complex molded body of the present invention is anisotropicin terms of carbon nanotube-specific properties, such as electricalproperty, thermal property, and mechanical property. In other words, thecomplex molded body has different degrees of such properties atdifferent directions.

[0038] For electrical property, the complex molded body of the presentinvention has high electrical conductivity in a certain direction. Inaddition, this molded body exhibits higher conductivity with a smalleramount of carbon nanotubes compared with a molded body in which carbonnanotubes are not arranged in a given direction. The electron emissionof carbon nanotubes is believed to be most efficient at the end ofnanotubes. According to the invention, carbon nanotubes may be placed sothat a larger number of ends of carbon nanotubes are placed at the edgeof the complex molded body.

[0039] For thermal property, when the carbon nanotubes are arranged in athickness direction of a plate-like molded body, thermal conductivity ina direction parallel to the arrangement direction of the nanotubes isdifferent from that in a direction perpendicular to the same. Since thecarbon nanotubes have greater thermal conductivity in their axialdirection than that in a direction perpendicular to the axial direction,the above plate-like molded body has greater thermal conductivity in athickness direction, which allows the molded body to be anisotropic. Inthis case, the carbon nanotubes are preferably graphitized to improvethermal conductivity.

[0040] For mechanical property, when the carbon nanotubes are arrangedin a thickness direction of a plate-like molded body, anisotropicelasticity is obtained. The tensile strength and bending strength in thethickness direction are improved.

[0041] Besides, the complex molded body of the present invention may beanisotropic in terms of magnetic property, electromagnetic property,linear expansion coefficient, dielectric property, and wave-absorbingproperty. Thus, the molded body may be used for various applicationssuch as a damping material and a wave-absorber.

[0042] The advantages of the above embodiments are described below.

[0043] In the embodiments, carbon nanotubes are arranged in a givendirection. Thus, properties (such as electrical property, thermalproperty, and mechanical property) of the molded body in a direction inwhich the carbon nanotubes extend is different from those in otherdirections. This allows the complex molded body to have excellentanisotropic functions that have never been achieved. Moreover, sincemicroscopic carbon nanotube is a minute material, such anisotropicfunctions can be achieved in a minute complex molded body.

[0044] In addition, the complex molded body may be anisotropic in termsof magnetic property, electromagnetic property, linear expansioncoefficient, dielectric property, and wave-absorbing property.Accordingly, the complex molded body may be used for variousapplications such as a pressure sensor, a sensing switch, a magneticshield material, magnetic recording material, and a magnetic filter.

[0045] With respect to the above embodiments, a magnetic field may beapplied to the composition that includes carbon nanotubes. Thus, thecarbon nanotubes may be arranged in a given direction in the matrixeffectively.

EXAMPLE

[0046] The above embodiments will be described by way of examples.Although the description is made on a plate-like complex molded body inExamples and Comparative examples, the invention is not limited in anyway by the examples.

[0047] In each example, carbon nanotubes were synthesized by a thermalcracking process using a catalyst, which is an example of syntheticmethod of carbon nanotubes. The cracking process is almost equal tocarbon fiber vapor phase epitaxy and will be described below.

[0048] Firstly, ethylene or propane as a source gas is introduced into athermostat together with hydrogen. A source gas may be saturatedhydrocarbons such as methane, ethane, butane, hexane, and cyclohexanone;unsaturated hydrocarbons such as propylene, benzene, toluene; andoxygen-containing material such as acetone, methanol, and carbonmonoxide.

[0049] Next, the source gas introduced into a thermostat is heated orcooled to control a vapor pressure. Then the gas is further introducedwith hydrogen gas into a thermal cracking reactor, where ethylene orpropane as a source gas is cracked to yield carbon nanotubes.

Example 1

[0050] A manufacturing device and a manufacturing method for making aplate-like complex molded body are described with reference to FIGS. 1to 4.

[0051] As shown in FIG. 2, a pair of forming molds 1 a, 1 b is placed tooppose to each other. A forming recess 2 is provided in the opposingsurface of the forming mold 1 a. The recess 2 matches to a intendedplate-like complex molded body. Both of the mold 1 a, 1 b are formed ofaluminum. The surface of the recess 2 is coated with fluororesin.

[0052] A composition 3 was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermosetting unsaturated polyesterresin (NIPPON SHOKUBAI CO., Ltd., a trade name of EPOLAC™ G-157 MB) andstirring. The composition 3 was filled in the recess 2.

[0053] As shown in FIG. 3, the molds 1 a, 1 b were closed together at acertain pressure to seal the recess 2. Then, as shown in FIG. 4, a pairof magnets 4 a, 4 b was placed on either side of the molding 1 a, 1 b. Anorth pole N of the magnet 4 a and a south pole S of the magnet 4 b wereopposed to each other. A magnetic field of 10 tesla was applied in adirection parallel to an inner bottom face of the recess 2. Then thecomposition 3 was left for 30 minutes at room temperature to behardened. After that, the mold 1 a, 1 b were opened to remove aplate-like complex molded body 5 of carbon nanotubes from the recess 2.

[0054] As seen in FIG. 1, the carbon nanotubes 6 in the resultantcomplex molded body 5 were arranged in a direction parallel to upper andlower faces of the mold 1 a, 1 b.

Example 2

[0055] A complex molded body 5 was obtained as in Example 1, except thata magnetic field of 10 tesla was applied in a direction perpendicular toan inner bottom face of the recess 2. As seen in FIG. 5, The carbonnanotube 6 in the resultant complex molded body 5 were arranged in adirection perpendicular to upper and lower faces of the complex moldedbody 5.

Example 3

[0056] A composition 3 was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermosetting epoxy resin (EpoxyTechnology, Inc., a trade name of EPO-TEK310) and stirring. Thecomposition 3 was filled in the recess 2 of the mold 1 a shown in FIG.2. Following the procedures as in Example 1, a complex molded body 5 wasobtained.

Example 4

[0057] A composition 3 was prepared by adding 2 parts by weight ofcarbon nanotubes to 100 parts by weight of thermosetting epoxy resin(Epoxy Technology, Inc., a trade name of EPO-TEK310) and stirring. Thecomposition 3 was filled in the recess 2 of the mold 1 a shown in FIG.2. Following the procedures as in Example 1, a complex molded body 5 wasobtained.

Example 5

[0058] A composition was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermoplastic polycarbonate resin(MITSUBISHI ENGINEERING-PLASTICS CORPORATION, a trade name of Iupilon™S-2000) and mixing with a screw extruder. Then methylene chloride wasadded to the composition and the mixture was stirred until the mixturebecame a uniform liquid. The resultant liquid was filled in the recess 2of the mold 1 a shown in FIG. 2. While a magnetic field of 10 tesla wasapplied in a direction parallel to an inner bottom face of the recess 2,the liquid was thermally hardened at 120 degrees C. for an hour toobtain a complex molded body 5.

Example 6

[0059] A complex molded body 5 was obtained as in Example 5, except thata magnetic field of 10 tesla was applied in a direction perpendicular toan inner bottom face of the recess 2.

Comparative Example 1

[0060] A composition was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermosetting unsaturated polyesterresin (NIPPON SHOKUBAI CO., Ltd., a trade name of EPOLAC™ G-157 MB) andstirring. The composition was filled in the recess 2. Then, without amagnetic field applied, the composition was left for 30 minutes at roomtemperature to be hardened to form a complex molded body. The carbonnanotubes were randomly dispersed in the complex molded body.

Comparative Example 2

[0061] A composition was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermosetting epoxy resin (EpoxyTechnology, Inc., a trade name of EPO-TEK310) and stirring. Thecomposition was filled in the recess 2 of the mold 1 a shown in FIG. 2.Then, without a magnetic field applied, the composition was left for 30minutes at room temperature to be hardened to form a complex moldedbody.

Comparative Example 3

[0062] A composition was prepared by adding 2 parts by weight of carbonnanotubes to 100 parts by weight of thermosetting epoxy resin (EpoxyTechnology, Inc., a trade name of EPO-TEK310) and stirring. Thecomposition was filled in the recess 2 of the mold 1 a shown in FIG. 2.Then, without a magnetic field applied, the composition was left for 30minutes at room temperature to be hardened to form a complex moldedbody.

Comparative Example 4

[0063] A pellet was prepared by adding 1 part by weight of carbonnanotubes to 100 parts by weight of thermoplastic polycarbonate resin(MITSUBISHI ENGINEERING-PLASTICS CORPORATION, a trade name of Iupilon™S-2000) and mixing with a screw extruder. Then 70 parts by weight ofmethylene chloride was added to 100 parts by weight of the pellet andthe mixture was stirred until the pellet was completely dissolved. Theresultant liquid was filled in the recess 2 of the mold 1 a shown inFIG. 2. Then, without a magnetic field applied, the liquid was thermallyhardened at 120 degrees C. for an hour to obtain a complex molded body.

[0064] For complex molded bodies obtained in Examples 1, 2, 5, and 6 andComparative examples 1 and 4, storage modulus E′, loss modulus E″, losstangent tan δ at a frequency of 11 Hz were measured using a dynamicviscoelasticity measuring system (ORIENTECH CO., Ltd., a trade name ofRHEOVIBRON DDV-III). The results were shown in Table 1. TABLE 1 amountE′ E″ (part by wt) direction (N/m²) (N/m²) tan δ Ex. 1 1 parallel  1.8 ×10⁵  2.4 × 10⁴ 0.13 Ex. 2 1 perpendicular  1.2 × 10⁵ 0.89 × 10⁴ 0.074Ex. 5 1 parallel  1.5 × 10⁶  2.2 × 10⁴ 0.14 Ex. 6 1 perpendicular 0.92 ×10⁶ 0.78 × 10⁴ 0.085 Comp. 1 1 no  1.1 × 10⁵ 0.87 × 10⁴ 0.078 Comp. 2 1no 0.95 × 10⁶ 0.80 × 10⁴ 0.084

[0065] Aside from the above measurement, for complex molded bodiesobtained in Examples 3, 4 and Comparative examples 2, 3, magneticsusceptibility χ from 0 to 5 T was measured using a SQUID susceptibilitymeasurement system (Quantum Design, Model MPMS-7). The results wereshown in Table 2. In Tables 2 to 4 below, measurement direction meansthe following:

[0066] Parallel: sample was measured in a direction parallel to thedirection in which the carbon nanotubes extend.

[0067] Perpendicular: sample was measured in a direction perpendicularto the direction in which the carbon nanotubes extend.

[0068] No: sample in which the carbon nanotubes were randomly dispersedwere measured. TABLE 2 amount measurement (part by wt) direction χ (/g)|Δχ| (/g) Ex. 3 1 parallel −6.4 × 10⁻⁵ 1.2 × 10⁻⁵ perpendicular −7.5 ×10⁻⁵ Ex. 4 2 parallel −8.2 × 10⁻⁵ 1.0 × 10⁻⁶ perpendicular −8.3 × 10⁻⁵Comp. 2 1 no −7.0 × 10⁻⁵ — Comp. 3 2 no −8.2 × 10⁻⁵ —

[0069] Further, for complex molded bodies obtained in Example 3 andComparative example 2, electric resistance was measured. The resultswere shown in Table 3. Electric resistance is a measured voltage acrossthe two terminals, when a direct current of 1 mA is passed through andthe distance between the terminals is 1 mm. TABLE 3 amount measurement(part by wt) direction resistance (Ω) Ex. 3 1 parallel 17.8 × 10³ perpendicular 1.14 × 10³ Comp. 2 1 no 6.06 × 10³

[0070] For complex molded bodies obtained in Example 1 and Comparativeexample 2, linear expansion coefficient at from 30 to 200 degree C. wasmeasured using a thermomechanical analyzer (Mettler, TMA-40, TA-3000).The results were shown in Table 4. TABLE 4 amount measurement linearexpansion (part by wt) direction coefficient (/degree C.) Ex. 1 1parallel 1.45 × 10⁻⁴ perpendicular 1.70 × 10⁻⁴ Comp. 2 1 no 1.57 × 10⁻⁴

[0071] Particularly, variations in magnetic susceptibility χ, or theabsolute value of the difference between the magnetic susceptibility ina parallel direction and that in a perpendicular direction |Δχ|, ofTable 2 show that Example 3 has magnetic anisotropy. Variations inelectric resistance of Table 3 show that Example 3 has anisotropy ofelectric resistance. Variations in linear expansion coefficient showthat Example 1 has anisotropy of linear expansion coefficient. Inaddition, Table 1 showed that the molded body of Example 1 has greaterstorage modulus E′ and loss modulus E″ in a parallel direction than in aperpendicular direction, indicating that the molded body of Example 1has an excellent elasticities in a direction parallel to the upper andlower faces of the molded body.

[0072] It should be apparent to those skilled in the art that thepresent invention may be embodied in many other specific forms withoutdeparting from the spirit or scope of the invention. Particularly, itshould be understood that the invention may be embodied in the followingforms.

[0073] The magnetic field applied to the composition 3 may be orientedin an oblique direction relative to the inner bottom face of the recess2 of the mold 1 a.

[0074] A coating of ferromagnetic material may be formed on the surfaceof the carbon nanotubes to arrange them effectively. This facilitatesthe anisotropic functions of the molded body.

[0075] Carbon fibers, such as graphitized carbon fibers, may be mixedwith the carbon nanotubes. This facilitates the anisotropy functions interms of thermal conductivity and electro-isolative property.

[0076] Metals, ceramics, other inorganic materials, or precursorsthereof may be used as a matrix. In such cases, a magnetic field isapplied to the matrix that is melted or dispersed in a solvent. Thematrix is then cooled to be hardened or dried or sintered to be hardenedto form a complex molded body. For example, an aluminum-alloycomposition including carbon nanotubes is melted in a container that hasa predetermined shape. Then a magnetic field is applied to thecomposition to arrange the carbon nanotubes in a given direction. Thecomposition is then cooled and hardened to form a complex molded body.This manufacturing method provides a resultant molded body with requiredcharacteristics such as hardness and anisotropy in terms of mechanicalstrength, heat resistance, electrical properties, and durability.

[0077] The matrix may be carbonized or graphitized. For example, thecomposition including phenol resin or epoxy resin as a matrix and carbonnanotubes is melted in a container that has a predetermined shape. Thena magnetic field is applied to the composition to arrange the carbonnanotubes in a given direction. The composition is then dried andsintered to carbonize or graphitize the matrix, thereby forming acomplex molded body. This manufacturing method provides a resultantmolded body with required characteristics such as hardness andanisotropy in terms of mechanical strength, heat resistance, electricalproperties, and durability.

[0078] Therefore, the present examples and embodiments are to beconsidered as illustrative and not restrictive and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalence of the appended claims.

1. A complex molded body of carbon nanotubes comprising: a matrix; andcarbon nanotubes arranged in a given direction in the matrix.
 2. Acomplex molded body of claim 1, wherein the matrix is at least oneorganic polymer selected from the group consisting of thermoplasticresin, thermosetting resin, rubber, and thermoplastic elastomer.
 3. Acomplex molded body of claim 1, wherein the matrix is metal, ceramic,other inorganic material, or a precursor thereof.
 4. A complex moldedbody of claim 1, wherein the carbon nanotubes have a diameter of 1 to 20nm and a length of 50 nm to 100 μm.
 5. A complex molded body of claim 1,wherein the amount of the carbon nanotubes is 0.1 to 20 parts by weightrelative to 100 parts by weight matrix.
 6. A complex molded body ofclaim 1, further comprising graphitized carbon fibers.
 7. A complexmolded body of claim 1, wherein the carbon nanotubes have aferromagnetic coating on their surface.
 8. A method of making a complexmolded body of carbon nanotubes comprising the steps of: providing acomposition that includes a matrix and carbon nanotubes; applying amagnetic field to the composition to arrange the carbon nanotubes in agiven direction; and hardening the composition to produce a complexmolded body.
 9. A method of claim 8, wherein the matrix is at least oneorganic polymer selected from the group consisting of thermoplasticresin, thermosetting resin, rubber, and thermoplastic elastomer.
 10. Amethod of claim 8, wherein the matrix is metal, ceramic, other inorganicmaterial, or a precursor thereof.
 11. A method of claim 8, wherein thecarbon nanotubes have a diameter of 1 to 20 nm and a length of 50 nm to100 μm.
 12. A method of claim 8, wherein the amount of the carbonnanotubes in said composition is 0.1 to 20 parts by weight relative to100 parts by weight matrix.
 13. A method of claim 8, wherein saidcomposition further includes graphitized carbon fibers.
 14. A method ofclaim 8, wherein the carbon nanotubes have a ferromagnetic coating ontheir surface.
 15. A method of claim 8, wherein the magnetic field has amagnetic flux density from 5 to 20 tesla.
 16. A method of claim 8,wherein the step of providing a composition includes injecting thecomposition into a recess of a forming mold.
 17. A method of claim 10,wherein the step of hardening the composition includes cooling thecomposition.
 18. A method of claim 8, wherein the step of hardening thecomposition includes drying and sintering the composition to carbonizeor graphitize the matrix.